* The IDE has been internationalized and translated into multiple languages. Thanks to Shigeru Kanemoto for the internationalization and Japanese translation and many others for the other translations. For more information, see: http://arduino.cc/playground/Main/LanguagesIDE

* Added preference for selecting the language in which to display the Arduino software. Defaults to the operating system locale.

* New upload process for the Arduino Leonardo (ATmega32U4).

* The editor font size preference now applies to the serial monitor and error / message console as well as the editor. (Paul Stoffregen) http://code.google.com/p/arduino/issues/detail?id=550

* Compilation has been speeded up by only compiling changed files. (All files are recompiled when a new board is selected.) (Paul Stoffregen) http://code.google.com/p/arduino/issues/detail?id=638

* Added the gcc toolchain to the Linux distribution. (To use the toolchain already installed on your system, simply delete the one that comes with the Arduino software.) (Paul Stoffregen) http://code.google.com/p/arduino/issues/detail?id=300

Added ability to generate repeated starts in the Wire library (in master mode). Extra boolean parameters to endTransmission() and requestFrom() control whether or not to send a stop (or a repeated start instead)